The present invention relates to a vehicular headlamp of a type having a moveable reflector in which the reflector with an attached light source is supported by an aiming mechanism so as to be tiltable relative to a lamp body. More particularly, the invention relates to a vehicular headlamp with a movable reflector in which the aiming screw, which is a structural member of the aiming mechanism, is formed from synthetic resin.
As is shown in FIG. 15, in a conventional vehicular headlamp of this type, a synthetic resin reflector 2 on which is mounted a light source is supported near the front surface of a synthetic resin lamp body 1 by an aiming mechanism formed from one ball joint, which is a tilting fulcrum, and two nut members. The nut members, which constitute moving support points capable of moving forward and backward in the axial direction, mesh with respective ones of the aiming screws.
More specifically, an aiming screw 4 is rotatably supported in a screw insertion hole la provided in the lamp body 1, and a synthetic resin nut member 5, attached to a bracket 2a that extends out from the reflector 2, meshes with a threaded portion 4a of the aiming screw 4, which protrudes toward the front of the lamp body 1. By rotating the aiming screw 4, the nut member 5 is made to advance or retreat along the aiming screw 4, whereupon the reflector 2 tilts about a tilt axis that connects the ball joint and the nut member that meshes with another aiming screw. As a result, the optical axis of the lamp can be adjusted.
The aiming screw 4 is made from metal and has a crown-shaped gear 7 formed integrally at the rear end portion thereof. The aiming screw 4 can be rotated using a screwdriver D. The aiming screw 4, which is inserted through the screw insertion hole 1a from the rear of the lamp body 1, is elastically supported in the longitudinal direction by a push-on fixing element 8 and is thereby held in position.
In addition, an O ring 9, which serves as a sealing member, is inserted in the screw insertion hole 1a that rotatably supports the aiming screw 4, thereby waterproofing the rotation support portion of the aiming screw 4.
However, in the above described lamp, because the aiming screw 4 is made of metal, there has been a limit as to how much the weight of the aiming mechanism and the headlamp could be reduced. Therefore, in recent years, proposals have been made to form the aiming screw out of synthetic resin in order to reduce the weight of the headlamp.
However, when the aiming screw is made of synthetic resin, a problem as described below has occurred, and thus an aiming screw made of synthetic resin has not been put to actual use prior to the invention.
Namely, as is indicated by the symbol W in FIG. 15, the weight of the reflector acts on the distal end of the aiming screw 4, which is supported in a cantilever fashion, resulting in the proximal end portion of the aiming screw 4 being easily deformed by bending and creating durability problems.
The nut member 5 attached to the reflector bracket 2a is formed so as to be able to rock slightly relative to the bracket 2a; however, it is not possible to reliably remove the stress generated in the attachment portion between the bracket 2a and the nut member 5. Therefore, problems arise such as the reflector 2 and the aiming screw 4 being deformed due to the stress generated in the attachment portion between the nut member 5 and the bracket 2a when the nut member 5 is made to advance or retreat along the screw upon rotation of the aiming screw 4, and therefore appropriate aiming is not always possible.
The present invention was conceived in view of the above situation, and it is an object thereof to provide a vehicular headlamp with a movable reflector in which appropriate aiming is ensured by the use of an aiming screw made from synthetic resin.
In order to achieve the above and other objects, a first embodiment of the present invention is provided in the form of a vehicular headlamp with a movable reflector, and which comprises a container-shaped lamp body made from synthetic resin, a front lens made from synthetic resin attached to a front surface aperture portion of the lamp body so as to define together with the lamp body a lamp compartment, a reflector with an attached light source and housed in the lamp compartment, and an aiming mechanism that is provided between the lamp body and the reflector and that supports the reflector tiltably relative to the lamp body, wherein the aiming mechanism includes an aiming fulcrum that forms a tilt fulcrum of the reflector, a synthetic resin aiming screw that is rotatably supported in a screw insertion hole provided in the lamp body and extends in a forward direction, and a synthetic resin nut member that is attached to a bracket formed extending from the reflector, that meshes with the aiming screw, and that is made to advance or retreat by a rotation of the aiming screw, and wherein a nut slide guide is formed integrally with the lamp body and extending outward so as to carry and support the nut member in a manner whereby it can slide in a longitudinal direction, and stress relieving means having a ball joint structure is provided at an attachment portion where the nut member is attached to the bracket for relieving stress that is generated in the attachment portion as the nut member is made to advance or retreat.
Because the nut slide guide that is formed integrally with the lamp body carries the weight of the reflector that is borne by a nut member that meshes with the aiming screw, the bending moment created by the weight of the reflector does not act on the synthetic resin aiming screw.
Moreover, the stress that is generated between the aiming screw and the reflector in the portion where the nut member is attached to the bracket when the reflector is tilted relative to the lamp body due to the forward or backward movement of the nut member or when the reflector undergoes thermal expansion due to heat emitted from the light source is relieved by the stress relieving means having a ball joint structure that is provided at the attachment portion of the nut member and the bracket.
Further, because the nut member that is made to advance or retreat longitudinally by the rotation of the aiming screw is guided in a direction along the aiming screw by the nut slide guide, it is possible to keep the frictional torque in the portion where the nut member meshes with the aiming screw constant.
The aiming mechanism may include a vertical aiming screw provided at a position where it can move vertically toward or away from the aiming fulcrum, and a horizontal aiming screw provided at a position where it can move horizontally toward or away from the aiming fulcrum.
The nut member that meshes with the vertical aiming screw is made to advance or retreat along the vertical aiming screw by the rotation of the vertical aiming screw and the reflector is tilted about a horizontal tilt axis that passes through the aiming fulcrum and the attachment portion of the bracket and the nut member that meshes with the horizontal aiming screw.
The nut member that meshes with the horizontal aiming screw is made to advance or retreat along the horizontal aiming screw by the rotation of the horizontal aiming screw and the reflector is tilted about a vertical tilt axis that passes through the aiming fulcrum and the attachment portion of the bracket and the nut member that meshes with the vertical aiming screw.
The attachment portion of the bracket and the nut member may be formed from a ball engaging projection that protrudes from a side surface of the nut member that faces the aiming fulcrum and a ball receiving engaging hole that is provided in the bracket and that is engaged by the engaging projection. Further, the stress relieving means with a ball joint structure is constructed with the engaging protrusion and the engaging hole formed so as to be slidable relatively in the engaging direction, so as to be swingable relatively on a plane that contains the aiming screw, and so as to be rotatable relatively in the engaging hole peripheral direction.
The engaging hole may be partitioned into two holes by a partition wall that is parallel with the aiming screw, in which case the engaging projection is divided into two pieces and the bifurcated engaging projections so formed are each inserted into the respective holes so that the bifurcated portion is engaged with the partition wall, and the engaging projections are held in a state of pressure contact with inner peripheral surfaces of the engaging hole.
The partition wall of the engaging holes and the bifurcated engaging projections act as a guide when the engaging projection is inserted into the engaging hole. Moreover, the engaging projection that has been inserted into the engaging hole is held in a state of pressure contact by the inner peripheral walls of the engaging hole so that it does not come out and also acts to prevent vibration in the attachment portion of the nut member and the bracket.
It is also possible to provide convex portions at the opposing outer peripheral surfaces of the bifurcated engaging projections that are both placed in pressure contact with the inner peripheral surface of the engaging hole and that form a relative swinging axis of the engaging protrusion and the engaging hole.
With this structure, the axis passing through the pair of convex portions that are in pressure contact with the inner peripheral surface of the engaging hole becomes the relative swing axis of the engaging protrusion and the engaging hole, and accordingly smooth swinging of the engaging projection and the engaging hole is ensured. As a result, the reflector tilts smoothly and smooth aiming is made possible.
The nut member may be accommodated in a cylindrical slide guide whose side surface on the aiming fulcrum side is open and which extends longitudinally so as to cover the aiming screw, while the engaging projection protrudes from the side surface aperture portion of the slide guide, and an elastic protruding portion shaped like a plate spring that slides in a state of pressure contact along the nut slide guide is formed on a side surface of the nut member.
The elastic protruding portion shaped like a plate spring is in pressure contact with the nut slide guide and the nut member is elastically supported inside the nut slide guide without looseness so that smooth sliding of the nut member along the nut slide guide (the aiming screw) is ensured.
Furthermore, it is also possible to form the screw insertion holes using a cylindrically shaped portion that is formed integrally with the lamp body and extends forward while penetrating the lamp body. Also, it is possible to form the forward extending portion of the cylindrically shaped portion from a plurality of divided swinging pieces that are divided in the peripheral direction and elastically deformable in the radial direction and which have anchoring portions formed in the distal ends thereof that engage with concave-shaped engaging portions in the aiming screw so as to stop the aiming screw that is inserted from the rear of the lamp body from falling out from the rear. Moreover, it is possible to provide the aiming screw with a supported section that is supported by the screw insertion hole, a male threaded portion in front of the supported portion, and a rotation operation portion behind the supported portion, and to integrally form the aiming screw with a skirt-shaped elastic waterproofing rib that is in pressure contact with and also slides over the peripheral edge portions of the screw insertion hole.
By using this type of structure, when the aiming screw is inserted into the screw insertion hole from the outer side of the lamp body, the divided swinging pieces that form the forward extending end portion of the cylindrically shaped portion are pushed by the supported portion and are elastically deformed. Accordingly, the diameter thereof is enlarged in the radial direction, the supported portions penetrate the cylindrically shaped portion and the anchoring portions of the divided swinging pieces engage with the concave-shaped engaging portions of the aiming screw, while the skirt-shaped elastic ribs abut against the peripheral edge portion of the screw insertion hole. Consequently, the aiming screw is fixed in position in the axial direction relative to the screw insertion hole.
The skirt-shaped elastic waterproofing ribs formed at the rear end of the supported portion of the aiming screw are in pressure contact with and slide against the outer peripheral edge of the screw insertion hole, thereby preventing the intrusion of water into the portion between the aiming screw supported portion and the peripheral edge portion of the screw insertion hole at the rear of the lamp body and also elastically supporting the aiming screw in the longitudinal direction.
Both the waterproofing ribs and the lamp body are made from synthetic resin, and the slidability between the two is ensured in the sliding contact portion between the water proofing ribs and the screw insertion hole peripheral edge portion. The rotation of the aiming screw is not in any way hindered. Moreover, the synthetic resin waterproofing ribs are not deteriorated by water as much as are rubber O rings.
As a result, the aiming screw is elastically supported with no looseness in the longitudinal direction in the rotation support portion by the skirt-shaped elastic waterproofing ribs that are formed integrally with the aiming screw and are in sliding contact and pressure contact with the peripheral edge portions of the screw insertion holes. Also, the waterproofing of the rotation support portion of the aiming screw is ensured. Accordingly, there is no need to insert sealing members such as O rings or elastic members such as push-on fixing members in the rotation support portion of the aiming screw. Moreover, the number of parts used to form the aiming mechanism is reduced, thereby compacting the structure of the aiming mechanism and simplifying the task of assembling the aiming mechanism.
The synthetic resin waterproofing ribs will not deteriorated by water, even after lengthy use, and the elastic support and waterproofing of the rotation support section of the aiming screw is guaranteed over a long period of time.
It is also possible to use a structure in which second annular elastic waterproofing ribs that are in sliding contact with the inner peripheral surface of the screw insertion hole are formed integrally with the supported section of the aiming screw.
In such a case, the second annular elastic waterproofing ribs that are in sliding contact with the inner peripheral surface of the screw insertion hole and are formed integrally with the supported section of the aiming screw are held in a state of pressure contact with the inner peripheral surface of the screw insertion hole, thereby ensuring the waterproofing of the rotation support portion of the aiming screw.
Moreover, because the synthetic resin waterproofing ribs have elasticity (flexibility), when the supported portion of the aiming screw is inserted into the cylindrically shaped portion (screw insertion hole), the second waterproofing ribs are elastically deformed and do not impede the assembling of the aiming screw in the screw insertion hole. In addition, the sliding contact portion between the second waterproofing ribs and the inner peripheral surface of the screw insertion hole does not impede the rotation of the aiming screw.
The synthetic resin second waterproofing ribs are not deteriorated by water as much as are rubber O rings.
As a result, because the rotation support section of the aiming screw is waterproofed in two locations by the waterproofing means that uses the elastic waterproofing ribs in the peripheral edge portion of the screw insertion hole in the lamp body outer side and by the waterproofing means that uses the second elastic waterproofing ribs in the inner portion of the screw insertion hole, it is possible to doubly ensure the waterproofing of the rotation support portion of the aiming screw.
The reflector may also be made from synthetic resin, and the aiming fulcrum formed from a ball joint comprising a ball portion made from synthetic resin that protrudes from one of the reflector and the lamp body and a ball receiving portion made from synthetic resin that is capable of engaging with the ball portion and that protrudes from the other of the reflector and the lamp body.
In addition to the aiming screw, by forming the reflector and the ball joint that comprises the ball receiving portion and the ball portion forming the aiming fulcrum from synthetic resin, the entire aiming mechanism can be made from synthetic resin.